Heretofore, as this kind of driving assistance devices, there are devices that make notification of a collision risk.
For example, there have been known such devices that display collision-risk notification information on an instrument panel of a vehicle or a monitor of a car navigation system.
Further, there has been known a head-up display that displays collision-risk notification information on a front window of a vehicle as being overlapped with a landscape ahead thereof.
In any of these driving assistance devices, collision-risk targets, such as a pedestrian, a vehicle and the like, are detected by a camera, a millimeter-wave sensor, or the like, so that information about the collision-risk targets such as a pedestrian and the like is warningly displayed.
For example, according to a driving assistance device disclosed in Patent Document 1, the warning display is made using a head-up display in such a manner that the collision-risk target such as a pedestrian or the like is encompassed with a rectangle.
In addition, when there are a plurality of collision-risk targets, a brightness of the rectangle that has most to be known is increased for the driver.
That is, in order to direct the driver's eyes to the collision-risk target, the brightness of the rectangle is adjusted depending on the degree of importance of the collision-risk target.